Brachytherapy (low dose rate or high dose rate) has been a common treatment modality for localized radiation treatment of gynecological tumors. Various types of applicators such as vaginal cylinders and tandem/ovoid applicator sets have been widely used. Stereotactic radiosurgery (SRS) has been recognized as an alternative to brachytherapy, since it also delivers conformal, localized radiation. The present invention deals with, but is not limited to, the radiosurgical treatment or conventional external beam radiation treatment of vaginal mucosa and surrounding tissue layers at risk.
In order to properly define the treatment volume, a vaginal cylinder with proper diameter is inserted into the patient's vagina. This approach is not uncommon for boost treatment(s) to the vaginal wall in conventional external beam radiation therapy. The challenge arises when higher fractional doses are used, and the vaginal cylinder position has to be reproducible with a high degree of precision for each treatment fraction.
Two potential errors need to be addressed: first, the incorrect cylinder position in relation to the radiation beams, and second, the inconsistent positional correlation between the cylinder and the patient's body. These two geometric errors will cause dosimetric errors. With the present invention both geometric error and dosimetric error can be reliably minimized.